Multiple use impression coping

ABSTRACT

A dental impression coping which includes a set of components including an attachment screw access means through the impression material and not more than one attachment screw, that may be used for both pick-up type (open tray) or transfer tray (closed tray) impression moulding techniques. The impression components include an impression coping having non-rotational features and height specific retention means having an outer surface with its bottom end configured to reside preferably below the gingiva surrounding the implant. Means exist on the impression coping, to attach the impression coping to the implant for use in a transfer type impression application. By providing a means to access the attachment screw through the impression material a second impression application, the pick-up type impression application, can be performed, using the same screw that can be used also for the first impression application the transfer type impression application.

FIELD OF THE INVENTION

This invention relates to the dental implant industry. Morespecifically, this invention relates to impression copings for use aseither a pick-up type or transfer type impression coping by the use ofone and the same impression coping including the same screw.

BACKGROUND OF THE INVENTION

For an artificial tooth (i.e. “dental restoration”) to closely replicatethe lost natural tooth that it replaces, the artificial tooth mustemerge from the gum tissue with a similar shape and contour, as did thenatural tooth. Currently, dental implants, which function as artificialtooth roots and anchors for prostheses, are embedded in the bone tissueof the maxilla and mandible. It is important that the gingiva and softtissue forms a good contour with the overlying bone where the implant isinstalled. Prior to the application of functional loads to the implant,healing components generally function to expand a transmucosal openingfrom the head of the implant fixture to a size that more nearlyapproximates the size, contour and profile of the tooth where it emergesfrom the gum. After the healing components have encouraged healing ofthe gingival tissue, an impression component is used to make a model ofthe patient's mouth in the area of the implant site. Today an impressiontaken directly of the head of the fixture and surrounding tissue isfrequently performed, especially in cases where early or immediateloading is possible. In such cases healing might not have started at thetime of impression taking and the transmuscosal opening has not yet beenexpanded or contoured.

Creating an artificial tooth or teeth for a patient who has been fittedwith one or more dental implants begins with taking this impression ofthe patient's case. Dental implants have locking means (externally orinternally) useful to interlock with corresponding locking means in thecomponents fitted to them when it is desired to prevent rotation of acomponent relative to the implant around the longitudinal axis of theimplant. An implant also has a machined interface to match acorresponding surface on the abutment or other components. This resultsin a tight seal preventing ingress of bacteria and ensures correctspatial orientation and alignment for a prosthesis. Once the implant hasbecome osseointegrated or achieves stable anchorage with the host bone,it becomes necessary to preserve in the impression the informationdescribing the orientation of its non-rotational connection and machinedinterface. Recording the correct orientation is critical if an accuratemodel of the patient's case is to be created in the dental laboratory.The component used to affect this information transfer is commonlycalled an “impression coping”.

By its very nature the impression material is resilient and elasticenough such that it can be removed from the patient's mouth after it hasset, and yet is of sufficient accuracy and stability such that it canpreserve geometric detail imparted to it by an impression coping. If thecoping used is a transfer type impression coping, it will remain in thepatient's mouth when the impression material is removed, pulling thetransfer coping out of the socket formed around it in the impression.This technique is known in the art as the “closed tray method” andrequires the implant analogue or fixture replica to be mounted on theimpression coping which is subsequently reinserted into the same socketbefore making the master cast. If the coping used is a pick-up typeimpression coping, it will remain within the impression when thematerial is removed from the patient's mouth. This technique is known inthe art as the “open tray method” and requires that the implant analogueis mounted on the impression coping, while the coping is still beingpositioned in the impression material, before making the master cast.

A problem that exists with current impression components is that thesame components used for pick-up type impression coping cannot be usedfor transfer type impression coping and vice versa This forcesmanufacturers to produce two separate lines of impression copingcomponents—one for pick-up type and one for transfer type. Moreover,clinicians are forced to maintain separate inventories of components tobe used with either method. In addition several manufacturers have a setof 3 or more different screws heights where there is restricted accessto the impression coping screw possibly because of a limitation in mouthopening for low-seated implants in order to get access to the impressioncoping screw.

U.S. Pat. No. 6,290,499 has tried to solve this but still there existstwo screws for either the pick-up type or transfer type impressioncoping methods and little chance to solve the impression of a low seatedimplant or restricted access.

Another nuisance for the clinician and the dental technician is thatwhen performing the transfer type impression coping method there is aneed to plug and remove the plug from the tool hole in the screw shaftand it is difficult to avoid bad seating from a tap formed by theimpression material in this hole.

A snap-on coping for the transfer type technique is proposed by NobelBiocare International Patent application No. WO 01/64127, but this willonly eliminate the screwing and unscrewing, not the need of differentcopings for different applications. In addition a snap on coping may notprovide the accuracy necessary and provided by two mating machinedsurfaces screwed together.

Therefore, it is an object of the present invention to provide animpression coping system which may be interchangeably used with eitherpick-up type or transfer type impression coping methods independent ofthe depth of the placed implant and restricted access and thateliminates bad seating and the use of multiple products to attach theimpression coping to the implant and the implant analogue.

It is a further object of the present invention to provide a method ofimpression coping and a method of dental restoration related theretowhich comprises the use of an impression coping as hereinbeforedescribed.

SUMMARY OF THE INVENTION

The impression components of the present invention include the improvedfeature of only requiring one single sized coping screw which is used toattach the coping component to the implant. By achieving access throughthe impression material to the coping screw by a mounted extender orthrough a superstructure on the coping screw or on the impression copingthe coping component may be used as a pick-up type impression coping.However, the same or an identical coping component and coping screw maybe used as a transfer type impression coping if no extender orsuperstructure is used. Therefore, the present invention allows onesingle coping and one single coping screw to be used for either pick-uptype or transfer type impression coping by achieving access to thecoping screw through the impression material.

Thus according to a first aspect of the invention we provide animpression coping system comprising an implant fastener or attachmentmeans adapted to engage with an implant and a coping component whichengages with the implant fastener and is adapted to support animpression material characterised in that the implant fastener andcoping component are adapted to be used for pick-up type (open tray)impression moulding techniques and/or transfer type (closed tray)impression moulding techniques.

A variety of implant fasteners may be used, but preferably the implantfastener is a coping screw which is adapted to engage with an implant.

This invention is described as a set of dental impression componentsthat may be used for both pick-up type (open tray) or transfer type(closed tray) impression moulding techniques. The components are usedwith an impression material to fabricate an impression at a site in ajawbone where an implant has been placed or reached a state ofosseointegration. The impression components include an impression copinghaving an outer surface with its bottom end generally configured toreside below the gingiva surrounding the implant and one single sizedcoping screw which is used to attach the coping component to the implantfor use in a transfer type impression application. By achieving accessto the coping screw through an additional component, an identical copingcomponent and an identical coping screw may be used as a pick-up typeimpression coping. This additional component can in some configurationsbe adjusted in height circumferential dimension by the clinician tocompensate for implant depth and restricted access providing even moreflexibility.

According to a further aspect of the invention we provide an impressioncoping system as hereinbefore described characterised in that theimplant fastener is adapted for use in pick-up type (open tray)impression moulding techniques and is provided with a mountable andremovable extension means which, in use, is sufficiently dimensioned soas to act as an extension of the implant fastener and protrude throughthe impression material (and typically the supporting impression tray).

According to a yet further aspect of the invention we provide animpression coping system according to claim 1 characterised in that theimplant fastener is adapted for use in transfer type (closed tray)impression moulding techniques and is provided with an attachment whichis adapted to space the implant fastener from the implant.

The invention also includes a coping screw spacer or spacer whichpreferably is mounted beneath the screw shaft during impression takingand then removed prior to re-seating in the set impression material inorder to avoid bad seating due to a tap formed by the impressionmaterial in the tool hole in the screw shaft when performing thetransfer type impression coping method.

It is a further object of the invention to provide a method ofimpression coping which utilise the systems hereinbefore described.

Thus, according to this aspect of the invention we provide a method ofmaking an open tray dental impression which comprises the steps of;

(i) placing a coping component on the implant fastener, the fasteneroptionally being equipped with a spacer;

(ii) engaging the fastener and coping component with an implant;

(iii) if the extender or superstructure is not already pre-mounted bymanufacturer, placing an extender component or superstructure componenton the fastener and/or coping component or any other suitable function,and optionally adjusting the height of the extender component orsuperstructure component;

(iv) moulding an impression material around the coping component and theextender;

(v) disengaging the coping component from the implant by unscrewing thescrew:

(vi) removing the impression moulded material (which at this point willcarry the coping component, fastener and extender or superstructure);

(vii) fitting the implant analogue to the coping component and thescrew; and

(viii) fabricating a master cast from the impression moulding containingthe implant analogue positioned on the coping component and completingthe transfer of the implant position from the oral cavity to a model ofthe oral cavity.

According to an alternative aspect of the invention we provide a methodof making a closed tray dental impression which comprises the steps of;

(i) placing a coping component on an implant fastener;

(ii) engaging the fastener, which is fitted with a spacer element, withan implant;

(iii) moulding an impression material around the coping component;

(iv) removing the impression moulded material;

(v) removing the spacer element from the fastener and fitting thefastener and coping component to the implant analogue; prior torefitting the coping component engaged with the implant analogue,preferably by the retention of the fastener, into the socket of theimpression material, by pushing the coping component and turning it tothe correct position determined by positioning means on the coping; and

(vi) fabricating a master cast from the impression moulding containingthe implant analogue positioned on the coping component and completingthe transfer of the implant position from the oral cavity to a model ofthe oral cavity.

It will be well understood by those skilled in the art that the stepsdescribed above need not be taken sequentially, rather the steps aremerely illustrative of the process. Therefore the methods ashereinbefore described should not be considered to be limited in such amanner.

The extension component as hereinbefore described is novel per se. Thusaccording to a yet further aspect of the invention we provide anextension component for use in a system as hereinbefore described. Avariety of such extension components may be used, however, preferablythe extension components may comprise a tubular sleeve, e.g. comprisinga plastic material. The extension component may be adapted to fit on thecoping component or, alternatively, on the implant fastener, butpreferably the extension component will form a snug fit around the outersurface of the implant fastener

Similarly, the spacer component as hereinbefore described is novel perse. Thus, according to another aspect of the invention we provide animplant fastener spacer component. The spacer preferentially comprisesan annular ring, and especially a split annular ring. It is found to beespecially advantageous for the spacer to be a split annular ring sincesuch a spacer may readily be removed as desired by the clinician using aconventional dental implement or by the dental technician.

It is a further novel aspect of the invention to provide the use of anextension component in a system or method as hereinbefore described.

It is also a novel aspect of the invention to provide the use of aspacer in a system or a method as hereinbefore described.

In another aspect of the invention we provide a kit suitable for pick-uptype (open tray) impression moulding comprising at least an implantfastener, a coping component and a extension member.

Alternatively we provide a kit suitable for transfer type (closed tray)impression moulding comprising at least an implant fastener, a copingcomponent and a spacer.

In relation to the aforementioned kits, it will be understood that a kitmay be provided which is suitable for both pick-up type and transfertype impression moulding.

Additional objects and features of the invention will be apparent in thefollowing description of exemplary embodiments of the invention withreference to the accompanying drawings. The scope of the invention isdelineated in the claims that are appended to this application.

BRIEF DESCRIPTION OF THE DRAWINGS

In the accompanying drawings:

FIG. 1 is a general view of a placed dental implant;

FIG. 2A is a side view of an impression coping representing an internalimplant abutment connection in the prior art;

FIG. 2B is a longitudinal section through FIG. 2A;

FIG. 2E is a top view of FIG. 2A;

FIG. 2F is a bottom view of FIG. 2A;

FIG. 2C is a side view of an impression coping representing an externalconnection in the prior art;

FIG. 2D is a longitudinal section through FIG. 2C;

FIG. 3A is a pick-up impression coping screw described in the prior art;

FIG. 3B is a pick-up impression coping arrangement described in theprior art assembled on a dental implant;

FIG. 4A is a transfer impression coping screw described in the priorart;

FIG. 4B is a transfer impression coping arrangement described in theprior art;

FIG. 4C is a pick-up impression coping arrangement described in theprior art assembled on an implant analogue;

FIG. 5A is a side view of an impression coping according to theinvention;

FIG. 5B is a longitudinal section through FIG. 5A;

FIG. 5C is a top view of FIG. 5A;

FIG. 5D is a bottom view of FIG. 5A;

FIG. 6A is a side view of an impression coping screw according to theinvention used for a transfer impression application;

FIG. 6B is a transfer impression coping arrangement with screw accordingto the invention assembled on a dental implant during impression taking;

FIG. 7A is a side view of an impression coping spacer according to theinvention;

FIG. 7B is a side view of an impression coping screw arrangement withscrew and spacer according to the invention;

FIG. 7C is a transfer impression coping arrangement with coping, screwand spacer according to the invention during impression taking;

FIG. 7D is a transfer impression coping arrangement with coping, screwand spacer according to the invention during master casting assembled onan implant analogue;

FIG. 8A is an impression coping screw according to the invention;

FIG. 8B is a superstructure for an impression coping screw according tothe invention used for a pick-up impression application;

FIG. 8C is a pick-up impression coping arrangement with coping, screwand superstructure according to the invention assembled on a dentalimplant;

FIG. 8D is an extender for a pick-up impression coping screw accordingto the invention;

FIG. 8E is a pick-up impression coping arrangement with coping, screwand extender according to the invention assembled on a dental implant;

FIG. 9 are the components according to the invention necessary toperform the impression following either the pick-up or the transferimpression technique;

DETAILED DESCRIPTION OF THE DRAWINGS

Prior Art Including Method

In FIG. 1 is shown an installed dental implant (1) which is fixed inbone (2) having overlying gingiva (3) with an opening (4) giving accessto the implant (1). The emergence profile (5) to be given to the opening(4) through the gingiva will depend on the type of tooth to be restoredand the position where the implant is installed. A healing abutmentprior to the impression taking has preferably contoured the emergenceprofile of the gingiva (3), but there are situations where an earlierloading or function of the prosthesis is wanted and an impression istaken before the final soft tissue contour is formed.

Referring to FIGS. 2A-F, two different impression coping components(6,7) are illustrated together with screws, FIGS. 3A-B, representing theprior art. The coping components have a top end, (8,9), and a bottomend, (10,11) and a through passage (12,13) from one end to the other.FIG. 2E is a view of the top end (8,9). FIG. 2F is a view of the bottomend (10,11). The coping component (6,7) is tubular in form, symmetricalaround its longitudinal axis A-A. At least one portion but preferably 2(18,19) or more of the outer surface of the coping (6,7) iscircumferentially recessed (20,21). At least one, but preferably two, ormore longitudinal recesses (23, 24) or ridged, are symmetrically arrayedaround the upper portion of the coping, extending from thecircumferentially recess (21, 22) to the upper end (8, 9). The recesses(23, 24) are formed on a circular locus, but that is by way of exampleonly. Recesses having other transverse-sectional shapes, such asrectangular and triangular, may also be used in copings of theinvention. An anti-rotation post (25) or socket (26) of known form, forexample polygonal such as hexagonal, octagonal or any anti-rotationmeans such as ridges, representing an external or internal implantabutment connection, is located in the bottom end (10, 11), preferablysymmetrical around the axis A-A. The through passage (12, 13) opens intothis anti-rotational socket (26) or extends through this anti-rotationalpost (25). A snap-on function, not shown, for engaging the impressioncoping to the implant mainly for the transfer type application can beincluded the said anti-rotational socket 26 or post 25.

A coping screw 27 (FIG. 3A) has a shaft 28 sized to fit in the throughpassage (12, 13), a threaded end 29 for engaging in a threaded bore inan implant 30 (FIG. 3B), and a head 31 for manipulating the screw 27,and for other uses to be presently described. As is shown in FIG. 3B,the head 31 abuts the end 8 of the coping component when the latter isfixed to the implant 30, which has an internally or externally matingsurface of known form to fit the anti-rotational socket or post of thecoping. The coping screw 27 of FIG. 3A is intended to be used in pick-uptype impression coping applications. The head 31 of the pick-up typecoping screw 27 is extended in length such that the top 32 of the copingscrew is positioned substantially above the top of the coping component33. This arrangement allows the coping screw 27 to be removed from thecoping component 33 after an impression has been taken with animpression material 34, thereby allowing the component 33 to remainwithin the impression material 34 as it is removed from the patient'smouth.

If a transfer type impression application, FIGS. 4A-C, is desired, anadditional coping screw 35 of FIG. 4A is used. The screw shaft 36 ofthis screw 35 is usually not equipped with any means such as slot or ainternal hex for the use of a screwdriver. Instead placement andretrievability is made by the use of the fingers since a slot or a hexwould interfere during reseating of the coping 37 after the impressiontaking and prior to the casting of the master model 38.

Referring now to FIGS. 3B and 4B, when the impression material 34 setsup around the coping component 33, 37 and coping screw shaft 32, 32′ animpression socket 40 is formed in the impression material 34 replicatingin reverse the shape and size of the coping 33, 37 and the protrudingpart 32, 32′ of the screw. Thus, for the annular recesses 20, 21 thereare an annular bulge 42, for each longitudinal recess 43 there is alongitudinal bulge 44 and for each projection 45 there is acorresponding recess 46.

Whenever the coping is reinserted into the socket 40, each of theprojections can occupy any of the corresponding recesses, thusreplicating only one possible orientation position of the copingdescribed above with reference to FIG. 2A or 2C. Additional objects andfeatures of the invention will be apparent in the following descriptionof exemplary embodiments of the invention with reference to theaccompanying drawings. The scope of the invention is delineated in theclaims that are appended to this application.

Systems of the Invention

(Transfer+Pick-Up Common Features)

An impression coping according to the invention is compatible withimplants or abutments as by known features of existing implant systemsbut can also be designed to be used with new implant systems andfeatures of the implant to abutment interface

This invention is described as a set of dental impression components,FIG. 5-10, that may be used for both pick-up type (open tray), FIG.8A-D, or transfer type (closed tray), FIG. 7A-D, impression mouldingtechniques. The components are used with an impression material tofabricate a model at a site in a jawbone where an implant has beenplaced or reached a state of osseointegration, FIG. 1, as described inthe prior art.

The impression components of the present invention include the improvedfeature of only requiring one single sized coping screw which is used toattach the coping component to the implant. The coping design can be ofa design proposed in FIG. 5A-D, or represented by the prior art, FIG.2-4.

The coping component 50 has a top end 47 and a bottom end 48, and athrough passage 49 from one end to the other. FIG. 5C is a view of thetop end. FIG. 5D is a view of the bottom end. The coping component 50 istubular in form, symmetrical around its longitudinal axis A-A. At leastone, preferably two (51, 52) or more portions, of the outer surface ofthe coping 50 is circumferentially recessed. At least one preferablytwo, or more, longitudinal recesses 53, 54 are symmetrically arrayedaround the upper portion of the coping, extending from the gingivalportion 55 to the upper end 47. The recess geometry of 51-54 is by wayof example only. The head 57 has a diameter D1, which is smaller thanthe diameter D2 of the coping component 50. This combination, FIGS.6A-B, forms a socket 58 in the impression material 59, which is narrowerat its interior end that it is at its open end to facilitate forre-insertion during the so called transfer impression techniquepreviously described. During reinsertion of the coping 45 into theimpression socket 58 the head 47 can “feel” the entrance to the narrowend and guide the coping into the socket while the impressioninterlocking elements 53, 54 are being manipulated around the axis A-A.An anti-rotation means, for example according to the prior artpreviously mentioned but here represented by an internal abutmentconnection means 60, FIG. 5A, is located in the bottom end 48,symmetrical around the axis A-A. The through passage 49 opens into thisanti-rotational means 60. The coping can also be prepared, FIG. 9, tohold a superstructure described later.

The coping 61 is attached, FIG. 6A-B, to the implant in known fashionusing a single screw 63 or for some applications, like the transfer typeapplication, an additional clamping type of fastening (not shown) canalternatively be used. The core component 61 is thereby fixednon-rotatably on the implant 62 and the same coping can be used for thepick-up type (open tray) or transfer type (closed tray) impressiontechnique. A coping screw 63 has a shaft 64 sized to fit in the throughpassage 49, a threaded end 64 for engaging in a threaded bore 66 in animplant 62, and a head 67 for manipulating the screw with a tool (notshown), and for other uses to be presently described. The head 67 maytake many forms. It may include a circumferential recess 68 as shown,for additional retention in the impression socket 58. It may omit anysuch recess. It may be shorter or longer than the head that isillustrated, FIG. 6A-B, but preferably extending outside the coping 61when it is in its screwed in position, FIG. 6B. It has means 70 toengage a driver or similar tool, not shown, for turning it. Self-guidingproperties like conical form of the screw seating surface can beincorporated in order to be optimised for the transfer type applicationaccuracy.

The impression taking arrangements, transfer and pick-up type, includingthe additional components modifying the screw and/or the screw accordingto the invention to make this dual use coping possible will hereforth bedescribed by first looking at the transfer application.

(Transfer)

Unlike the prior art, FIGS. 3 and 4, for the transfer type application,the screw 63 according to the invention, as described in FIGS. 7A-D, isequipped with a head 67 for manipulating the screw with a driver or atool, this head being preferably of similar diameter as the shaft 64.Still the placement and retrievability may be made by the use of thefingers. According to FIG. 7A-D, the re-seating difficulties of theimpression coping arrangement (impression coping 77, impression copingscrew 78 and spacer 86) in to the impression material 75 afterimpression taking due to the formation of an impression material portion76 formed in the means 79 to engage a driver for turning using such ascrew 72, 78 can be avoided by lowering the engagement portion 73 of thescrew 78 the distance A relative to the impression coping 77 prior tothe casting of the master model. The lowering is preferably performed bythe removal of spacer or shims 80 under the screw shaft 74. The spacer81 is preferably introduced or positioned, FIG. 7B, under the screwshaft before delivery to the end user and remains in place duringimpression taking, FIG. 7C. Prior to mounting and fastening the implantanalogue on the impression coping by the screw 78, the spacer 80 isremoved from the screw 78, for example peeled of with a pair of twistersor a scalpel, and thereby creating a void 88 when reinserted into theimpression material. After this the conventional casting of the mastermodel, FIG. 7D, can take place,

The invention, FIG. 7A-D, also includes the method of using a copingscrew spacer 80, 81 which preferably is mounted, FIG. 7B, beneath thescrew shaft during impression taking, FIG. 7C, on the implant 82 in thebone 85 and then the spacer 80 is removed prior to re-seating, FIG. 7D,in the cured impression material 75 and mounting on an fixture replica,implant replica or implant analogue, in order to avoid bad seating dueto a tap 76 formed by the impression material in the tool hole 79 of thescrew 72, 78 when performing the transfer type impression coping methodand forming the master cast 84 creating a void or a space 88 in theimpression material where the screw engagement portion 73 was before thespacer 80 was removed.

The spacer can be in the form of an open ring 86, tube or cylinderplaced around the screw neck 87 under the screw shaft 74, the height Hpreferably of larger height H′ than the inner tool connection of theattachment means 72, 78, said spacer being removed prior to reinsertionof the impression coping 77 in the impression material 75.

In addition or independently the spacer 86 can function as a retentionelement between the inner recess or through passage 49 of impressioncoping and the screw 72, 78, thus avoiding the screw from falling outfrom the impression coping during carrying, placement or disengagementof the impression coping assembly. The material of the spacer ispreferably a plastic material. In one embodiment the spacer is made inan elastic material which as a result of the lower torque duringattaching it to the implant 82 compared to the higher torque attachingit to the implant analogue 83 by compressing the spacer 80, is creatingthe space 88 and thus making it unnecessary to remove the spacer 80.

(Pick-Up)

According to the invention, in complement to the transfer typeapplication the same coping and coping screw can be used to perform thepick-up type application using the additional components, arrangementand method described in the following; using the identical copingcomponent 96 and an identical coping screw 89 as previously describedfor the transfer type application, FIGS. 7A-D, the pick-up typeapplication, FIGS. 8A-E, can be performed by achieving access andsubsequent screwing and unscrewing possibility to the coping screw 89through the impression 90, 91 material by an additional component. Thisadditional component can be a superstructure 92, FIG. 8B-C, forming asubstantially straight channel 92′ from the screw 89 past the uppersurface 93 of the impression material 90 for the access of a screwdriver(not shown) to the screw 89, or an extender 94, FIG. 8D-E. Thisadditional component can in some configurations be adjusted 95 in heightH″ by the clinician providing even more flexibility.

The superstructure 92 is preferably in the form of a tube thatpreferably is mounted by the user on upper portion 105 of the screwshaft protruding the height H′″ above the impression coping 96 prior tothe impression taking, FIG. 8C. Another preferred embodiment (not shown)is when a superstructure 92 instead is being placed mainly in contactwith the coping 96. In general the tubular passage 92 is being made inplastic.

The method characterising the use of the superstructure 92 is that thecoping 96 is positioned on the implant 100 and secured thereon by themeans of a screw or attachment 89 through an internal channel 92′. Thetube 92 is thereafter placed on the screw part 105 protruding above H′″the coping 96 and then the impression taking can take place according towell-known practice. After the impression material has set the screw isloosened by introducing a screwdriver device through said channel andsubsequently turned. The impression material 90 with coping 96, screw 89and tube 92 is lifted off from the implant 100. An implant analogue, thesame 83 type as for the transfer type application, is secured (notshown) on the coping 96 by means of the screw 89 though the channel 92′and then a master cast or model is made according to general methodsknown by the dental profession.

The optional embodiment of an extender 94, FIG. 8D-E, instead of asuperstructure 92 features a tool end 101, a shaft 102 penetrating theimpression material 91 and an upper portion 103. The upper portion 103can feature a tool hole which can be the same as the tool hole 104 inthe screw shaft or it can be designed for being rotated by the use offingers or a combination of both in order to transmit torque force forunscrewing and screwing of the screw 89 during the impression takingprocedure or method including the making of the master cast and themounting of an implant analogue or replica on the impression copingpreviously described.

Therefore, as summarised in FIG. 9, the design of this impression copingarrangement further provides the advantage of enabling the use of asingle coping component 106 for either transfer impression coping orpick-up impression coping applications. The coping 106 is designed toaccept one single coping screw 107 with the screw in the preferredembodiment designed to accept a spacer 108 and superstructure in theform of a tube 109. Since a single coping component may be used foreither impression coping method, a clinician is now able to easilyselect the most appropriate impression coping method for a given case.This choice can even be made during practice, for example duringsurgery. A clinician need only to mount or remove the extender orsuperstructure used with the coping component in order to changetechniques depending on if they where pre-mounted or not. Moreover, thisnew design feature requires only one coping component to be manufacturedand inventoried contrary to the manufacture and inventory of twoseparate coping screw components in the past (one for pick-up typeapplications and one for transfer type applications (including a numberof screw types and lengths). Therefore, this invention provides for amore modular design that is more economical for clinicians andmanufacturers since only one type of coping component needs to bemanufactured, purchased, and inventoried.

The impression coping arrangement may take a somewhat conical orpyramidal form, which has an advantage when taking an impression of acase having two copings on divergent axes. In such a case, if the twocopings are cylindrical they will have remote surfaces that diverge,making it difficult to remove the copings from an impression. Theconical form made possible in the present invention prevents divergenceof the remote surfaces over a wide range of divergent axes.

Accordingly, in the claims that follow, the term “coping” is intended toencompass any structure or combination of structures that forms theimpression socket 58.

The present invention thus presents a new and inventive step to performa transfer or pick-up type of impression technique using a singlecoping, a single screw, an access means and a spacer. At the time ofthis invention, the description above provides the optimal configurationof the coping component, which employs a superstructure or extender inco-operation with the customary pick-up or transfer impressionprocedure. However, it is to be understood that other embodiments arepossible, and are intended to be embraced within the scope of theappended claims.

While the present invention has been described with reference to one ormore preferred embodiments, those skilled in the art will recognise thatmany changes may be made thereto without departing from the spirit andscope of the present invention which is set forth in the followingclaims.

REFERENCES

-   DIA™. Dental Imaging Associates, Inplamed—The Source, The Anatomical    Abutment System, Copyright Date Oct. 9, 1991 on p. 10 (front cover,    pp. 1-10, and back cover).-   Lewis et al., Single Tooth Implant Supported Restorations,    International. Journal. of Oral & Maxillofacial Implants, vol. 3,    No. 1, pp. 25-30, 1988.-   Lewis et al., The “UCLA” Abutment, International. Journal. of Oral &    Maxillofacial Implants, vol. 3, No. 3, pp. 183-189, 1988.-   Prosthetic Catalog, 1993, Implant Innovations, Inc. (3 pages).-   Prosthetic Catalog, Impression Copings, Implant Innovations, Inc. (3    pages).-   Zarb, George A. and Thomas Jansson, Tissue-Integrated Prostheses,    Osseointegration in Clinical Dentistry, Chapter 17, Laboratory    Procedures and Protocol, pp. 293-315, 1985.-   Technical information and product catalogue, 2000, Advent and    Screw-Vent implant system, Paragon implant company.

1. An impression coping system comprising an implant fastener orattachment means adapted to engage with an implant and a copingcomponent which engages with the implant fastener and is adapted tosupport an impression material characterised in that the implantfastener and coping component are adapted to be used for pick-up type(open tray) impression moulding techniques and/or transfer type (closedtray) impression moulding techniques.
 2. An impression coping systemaccording to claim 1 characterised in that the implant faster isprovided at an implant engaging end with a screw thread.
 3. Animpression coping system according to claim 2 characterised in that theimplant faster is a coping screw.
 4. An impression coping systemaccording to claim 1 characterised in that the implant fastener isadapted for use in pick-up type (open tray) impression mouldingtechniques and is provided with a mountable and removable extensionmeans which, in use, is sufficiently dimensioned so as to act as anextension of the implant fastener and protrude through the impressionmaterial.
 5. An impression coping system according to claim 4characterised in that the extension means is adapted to form a snug fiton the external surface of the body of the fastener.
 6. An impressioncoping system according to claim 5 characterised in that the extensionmeans comprises a tubular sleeve.
 7. An impression coping systemaccording to claim 6 characterised in that the tubular sleeve isprofiled.
 8. An impression coping system according to claim 6characterised in that the tubular sleeve is adapted to be cut to anappropriate length.
 9. An impression coping system according to claim 6characterised in that the tubular sleeve comprises a plastics sleeve.10. An impression coping system according to claim 4 characterised inthat the extension means is adapted to stay in the impression materialafter impression.
 11. An impression coping system according to claim 4characterised in that the tubular passage is adapted to stay on theimplant fastener and thereby is removed from the impression materialafter impression.
 12. An impression coping system according to claim 4characterised in that the extension member is placed mainly in thecontact coping by the manufacturer.
 13. An impression coping systemaccording to claim 1 characterised in that the implant fastener isadapted for use in transfer type (closed tray) impression mouldingtechniques and is provided with an attachment which is adapted to spacethe implant fastener from the implant.
 14. An impression coping systemaccording to claim 13 characterised in that the implant faster isprovided with a fastening region
 15. An impression coping systemaccording to claim 14 characterised in that the fastening region is ofnarrower diameter than the body of the fastener.
 16. An impressioncoping system according to claim 14 characterised in that the fasteningregion an implant engaging end with a screw thread.
 17. An impressioncoping system according to claim 15 characterised in that the fasteningregion is provided with a shoulder.
 18. An impression coping systemaccording to claim 13 characterised in that the spacer is adapted to beremoved by a conventional dentistry implement or finger
 19. Animpression coping system according to claim 13 characterised in that thespacer is an annular ring.
 20. An impression coping system according toclaim 19 characterised in that the spacer comprises an annular splitring.
 21. An impression coping system according to claim 1 characterisedin that the coping component comprises an annular sleeve.
 22. Animpression coping system according to claim 21 characterised in that theannular coping sleeve comprises a slidable sleeve
 23. An impressioncoping system according to claim 22 characterised in that the annularcoping sleeve is rotatably slidable.
 24. An impression coping systemaccording to claim 1 characterised in that the coping sleeve adapted tobe supported by a surface of the implant.
 25. An impression copingsystem according to claim 1 characterised in that the implant isprovided with a shoulder for supporting coping sleeve.
 26. An impressioncoping system according to claim 21 characterised in that the diameterof coping sleeve is substantially the same as the diameter of theimplant.
 27. An impression coping system according to claim 13characterised in that the spacer is placed mainly in contact with thefastening region by the manufacturer.
 28. A method of making an opentray dental impression which comprises the steps of; (i) placing acoping component on the implant fastener, the fastener optionally beingequipped with a spacer; (ii) engaging the fastener and coping componentwith an implant; (iii) if the extender or superstructure is not alreadypre-mounted by manufacturer, placing an extender component orsuperstructure component on the fastener and/or coping component or anyother suitable function, and optionally adjusting the height of theextender component or superstructure component; (iv) moulding animpression material around the coping component and the extender; (v)disengaging the coping component from the implant by unscrewing thescrew: (vi) removing the impression moulded material (which at thispoint will carry the coping component, fastener and extender orsuperstructure); (vii) fitting the implant analogue to the copingcomponent and the screw; and (viii) fabricating a master cast from theimpression moulding containing the implant analogue positioned on thecoping component and completing the transfer of the implant positionfrom the oral cavity to a model of the oral cavity.
 29. A method ofmaking a closed tray dental impression which comprises the steps of; (i)placing a coping component on an implant fastener; (ii) engaging thefastener, which is fitted with a spacer element, with an implant; (iii)moulding an impression material around the coping component; (iv)removing the impression moulded material; (v) removing the spacerelement from the fastener and fitting the fastener and coping componentto the implant analogue; prior to refitting the coping component engagedwith the implant analogue, preferably by the retention of the fastener,into the socket of the impression material, by pushing the copingcomponent and turning it to the correct position determined bypositioning means on the coping component; and (vi) fabricating a mastercast from the impression moulding containing the implant analoguepositioned on the coping component and completing the transfer of theimplant position from the oral cavity to a model of the oral cavity. 30.An impression coping according to claim 13 wherein a means of theimpression coping screw is only removed for the transfer type (closedtray) impression moulding techniques to decrease the height of the screwshaft after impression taking and prior to reinsertion of the impressioncoping in the impression material for the making of a master cast forthe transfer type application, and thereby increasing the accuracy ofthe transfer type impression application said means being a spacer inthe form of an open or closed ring, tube or cylinder placed around thescrew neck under the screw shaft, the height preferably of larger heightthan the inner tool connection of the attachment means, said spacerbeing removed prior to reinsertion of the impression coping in theimpression material.
 32. An impression coping according to claim 13wherein a means of the impression coping screw is removed to decreasethe height of the screw shaft after impression taking and prior toreinsertion of the impression coping in the impression material for themaking of a master cast for the transfer type application, and therebyincreasing the accuracy of the transfer type impression application saidmeans being a spacer in the form of an open or closed ring, tube orcylinder placed around the screw neck under the screw shaft, the heightpreferably of larger height than the inner tool connection of theattachment means, said spacer being exhibiting elastic properties insuch way that the height of the spacer depends on torque levels thusbeing unnecessary to remove, said torque levels being higher for theattachment for the model making on the implant analogue than for themodel taking on the implant.
 33. A dental impression coping systemaccording to claim 1 for co-operating with an impression material totake an impression for making a model of a region in a mouth adjacent toan aperture in gingiva which exposes an implant that is installed inbone for pick-up type (open tray) and/or transfer type (closed tray)impression moulding techniques, said system comprising: a non-rotationalfitting for mating with a corresponding fitting of said implant; anouter surface having a transgingival section configured to fit withinsaid aperture and a supragingival section for embedment in saidimpression material, said supragingival section having at least one partwith a non-circular cross-sectional, said impression coping capable ofbeing transferred back into said impression material after saidimpression is taken preferably if using a transfer type impression mouldtechnique; a means intended for fastening or clamping said impressioncoping to said implant, an inner surface defining a passage that isgenerally aligned with said implant for receiving an attachment meansintended for fastening said impression coping to said implant: anattachment means intended for fastening said impression coping to saidimplant providing the said impression coping a superstructure orextender being able to be mounted in contact with said attachment meansor said impression coping providing a means to access the saidattachment means through the said impression material also providing thesaid impression coping to be used with the said pick-up impressionapplication.
 34. The impression coping of claim 1 wherein said implantfastener or attachment means for pick-up type (open tray) and/ortransfer type (closed tray) coping component relies upon on friction,elastics or mechanical interlocking.
 35. The impression coping of claim1 wherein the outer surface of the coping component is provided with aplurality of recesses.
 36. An impression coping according to claim 1wherein a spacer attached to screw can exhibit the retention of theattachment means being a screw, to the impression coping inner recessavoiding the part to disengage during carrying, placing and removal fromthe implant or implant analogue.
 37. An extension component for use in asystem according to claim
 4. 38. An extension component according toclaim 37 characterised in that the extension component comprises atubular sleeve.
 39. The use of an extension component in a methodaccording to claim
 28. 40. The use of an extension component in a systemaccording to claim
 4. 41. The use of a spacer in a method according toclaim
 29. 42. The use of a spacer in a system according to claim
 13. 43.A spacer component for use in a system according to claim 1
 44. A spacercomponent according to claim 43 characterised in that the spacercomprises an annular ring. removing the superstructure or extender priorto model taking if using the transfer type application applyingimpression material into said mouth and around said at least one firstand second interlocking recesses of said coping, said second recesshaving a predetermined angular orientation with respect to saidimpression material after being applied around said coping; if usingsaid transfer type application removing said impression material fromsaid mouth and then removing the impression coping from the implant byunscrewing the screw by hand or by screw driver followed by mounting theimplant analogue on the impression coping after having removed thespacer on the impression coping screw and subsequently reinserting saidimpression coping into an opening, preferably the same it was earlierremoved from, within said impression material: if using said pick-upapplication removing said impression coping from the implant byunscrewing the screw through the said access means, superstructure orextender followed by moving said impression material and impressioncoping arrangement from said mouth and mounting the implant analogue onthe impression coping; the casting of the stone model is then madeirregardless of pick-up or transfer type impression technique.
 51. A kitsuitable for pick-up type (open tray) impression moulding comprising atleast an implant fastener, a coping component and an extension member.52. A kit suitable for transfer type (closed tray) impression mouldingcomprising at least an implant fastener, a coping component and aspacer.
 53. An impression coping system or a method substantially asdescribed with reference to the accompanying examples.